超声振动辅助激光熔化沉积316L不锈钢的微观组织演变  

Microstructural Evolution of 316L Stainless Steel Prepared by Ultrasonic Vibration Assisted Laser Melting Deposition Technique

作　　者：柴鹏涛 刘学[1] 李晋锋[1] 刘政豪[1] 杨晓珊 周昱昭 王小英[1] 董鲜峰[1] 乐国敏[1] Chai Pengtao;Liu Xue;Li Jinfeng;Liu Zhenghao;Yang Xiaoshan;Zhou Yuzhao;Wang Xiaoying;Dong Xianfeng;Le Guomin(Institute of Materials,China Academy of Engineering Physics,Mianyang 621908,China)

机构地区：[1]中国工程物理研究院材料研究所,四川绵阳621908

出　　处：《稀有金属材料与工程》2020年第12期4177-4184,共8页Rare Metal Materials and Engineering

基　　金：国家重点研发计划(2017YFB0702400);国家自然科学基金(51871203,11605164)。

摘　　要：在激光熔化沉积316L不锈钢的过程中耦合不同功率的超声振动,研究了超声功率对晶粒形态、尺寸、凝固组织形成机制以及晶粒生长特性的影响。研究表明,激光熔化沉积过程中316L不锈钢晶粒发生定向凝固外延生长,形成粗大的柱状晶。施加超声会将沿[100]方向外延生长的粗大原生柱状晶打碎,产生细化晶粒的效果;沿柱状晶外延生长方向传递的超声振动增大了晶粒内沿长轴方向的累积取向差,提高了平均位错密度。施加超声有助于加强熔池流体的对流,降低沿沉积方向的温度梯度,使得垂直生长的柱状晶更快转变为八字形柱状晶;同时提高合金凝固冷速,使得柱状晶宽度以及晶粒内部一次枝晶列间距减小,实现宏观晶粒尺寸与微观枝晶间距的细化。Ultrasonic vibration with different ultrasonic powers of 0,600,1000 and 1400 W was applied during laser melting deposition of 316 L stainless steel.The effects of ultrasonic power on the grain morphologies and sizes,the microstructure formation mechanism and grain growth characteristics of 316 L stainless steel were studied.The results show that the application of ultrasonic vibration can break large sized columnar grains of the directional epitaxial growth,resulting in a refinement of microstructure,and increase the accumulative misorientations and dislocation densities along the long axis of grains.By promoting the convections in the melt pool,and reducing the temperature gradient along the deposition direction,the application of ultrasonic vibration accelerates the transitions of growth directions for columnar grains.The application of ultrasonic vibration also helps to increase the cooling rate during solidification,resulting in refinements of both columnar grains and the interior columnar dendrites.

关 键 词：超声振动 激光熔化沉积 316L不锈钢 微观组织 

分 类 号：TG142.71[一般工业技术—材料科学与工程]